Allows users to authenticate to SchoolTool using LDAP.

Deployment
----------

Here is what it takes to get this plugin deployed:

1) schooltool.ldap needs to be in the path (whether as an egg or as
   part of a sandbox)

2) you can configure ldap before first start by adding to schooltool.conf::

    %import schooltool.ldap
    <ldap_authentication>
      uri ldap://localhost:389
    </ldap_authentication>

3) or through the web from the Server tab.

See http://book.schooltool.org/ldap.html for more information
